1. Field of the Invention
The present invention relates to a sheet conveying apparatus for use in an image forming apparatus such as, for example, a copying machine, printer or a facsimile apparatus, for performing recording on a sheet-type recording medium such as a sheet of paper, an overhead projector transparency, an envelope or the like.
2. Description of the Related Art
FIG. 13 shows an electrophotographic laser beam printer as an example of known image forming apparatuses. In this printer, a sheet-like recording medium is fed and conveyed linearly to achieve a high degree of reliability in the sheet conveying operation. This type of sheet conveyance will be referred to as "straight-type sheet conveying method".
This type of sheet conveying method, however, requires a large space for the installation of the recording apparatus because of the area necessary for the sheet inlet portion to be situated, as well as the area where the sheet outlet portion is to be disposed.
In view of the above-described problem, U-type and S-type sheet conveying systems have been proposed in which, as shown in FIGS. 14 and 15, the paths of conveyance of the sheet is curved in a U or an S-shape, so as to reduce the installation area of the recording apparatus.
A sheet conveying apparatus also has been proposed in which a sheet as a recording medium is pinched only at one end by a conveyor roller and a skewed feeding roller, so that the sheet is fed and conveyed with a reference side edge thereof pressed against and guided by a conveyance reference surface provided in the image forming apparatus without skewing with respect to the direction of the conveyance despite the presence of the skewing bias applied thereto. This type of conveying method is generally referred to as "single-side skewed sheet conveying method".
This type of conveying method, however, suffers from a problem such as buckling at the reference side edge or inferior precision of the conveyance, due to the fact that the sheet is generally not still.